1. Technical Field of the Invention
This invention relates to switching structures comprising cores with coils and permanent magnets, intended for applications including DC relays, RF microwave switches and other similar switching components and applications.
2. Description of Related Art
While there have been a number of advances in the technology relating to all-electronic switching devices in recent years, there remain many applications for which such devices cannot replace their electromechanical magnetic counterparts. As a consequence, a need continues for highly reliable electromagnetic actuators for switching applications, especially where a switching device is subject to high impact and/or vibration, high acceleration, or widely varying environmental conditions.
Many examples of existing electromagnetic switching devices such as relays, capable of reliable operation under such demanding conditions, exist in the art; however, most are complex and comprise a number of components which are typically expensive and difficult to manufacture.
Reliable operation of these devices often depends upon precision machining and costly alignment, further complicating mass production techniques and adding to manufacturing costs. The Model 412K-Series TO-5 Relay manufactured by the Teledyne Corporation, discussed in the present inventor""s U.S. Pat. No. 5,272,458, is an example of existing electromagnetic switching devices described above. The invention of U.S. Pat. No. 5,272,458 obviated the limitations associated with the Model 412K-Series TO-5 Relay and similarly conceived switches and devices by providing a solenoid actuator which is highly reliable, simple to construct, relatively inexpensive to manufacture, and is able to withstand the severe operating and environmental conditions identified herein.
The invention presented in U.S. Pat. No. 5,272,458, while supplying the industry with a highly successful actuator, is not without its limitations. In order to achieve various failsafe, latching and other useful switching functions, it is necessary to change the basic design by altering the ferromagnetic mass which attracts the permanent magnet of the slider to its second position, or by reversing the current flow of the electromagnet to alter its poles, or both. In other words, one design cannot perform more than a single switching function. Clearly, a similarly simple design which can be used to perform a plurality of switching functions without such alterations would be a marked improvement over the invention of U.S. Pat. No. 5,272,458.
It is an object of the present invention to provide an improved design which is capable of performing a plurality of switching functions without fundamental alteration.
It is a further objective to provide a design which is highly reliable, simple in construction, relatively inexpensive to manufacture, and is able to operate under the extreme conditions typically found in applications requiring such devices.
An apparatus for switching applications in accordance with a preferred embodiment of the present invention includes one or more coaxially aligned electromagnetic coils separately wound on a common bobbin having a core of ferromagnetic material, a first rare earth permanent magnet within a magnet holder coaxially aligned with the core and located in close proximity to an end of the core, and a second rare earth permanent magnet positioned within the core. The magnet holder with first permanent magnet is constrained to move in a limited direction along the axis of the bobbin core between a first and second position by a channel defined by a magnet holder housing. By aligning the north and south poles of the two permanent magnets in relation to each other and the poles of the electromagnet formed by the electromagnetic coils and core, motion of the magnet holder including the first permanent magnet both toward and away from the bobbin core can be readily induced by applying voltage across the leads of the electromagnetic coils. This motion can be used to move a switching means back and forth between two positions relating to the first and second positions of the magnet holder to perform various failsafe, latching and other useful switching functions.
These and further advantages and structural details will be better understood in view of the detailed description below and the accompanying drawings.